What is Haemophilus parainfluenzae and is it Actually a Good Gut Microbe?

July 03, 2022 6 min read

What is Haemophilus parainfluenzae and is it Actually a Good Gut Microbe? - Layer Origin Nutrition

What is Haemophilus parainfluenzae and is it Actually a Good Gut Microbe?

In our series of articles about the 15 good gut microbes identified in the PREDICT studies, we’ve presented you with the latest research to show why they can be considered 'good'.

Now we meet Haemophilus parainfluenzae.

Yes, the observant amongst you might have noticed that buried inside that name is the word influenza.

So, just how good is H. parainfluenzae?

A quick online search of ‘Haemophilus parainfluenzae’ will show you that lots of research recognizes this microbe as a pathogen — that is, an organism that can cause disease to a host, and in the case of this microscopic creature, there are a few it has been associated with.

But it’s not altogether bad, and everyone deserves a second chance, don’t they?

That may be the case for H. parainfluenzaebecause researchers from the PREDICT studies have identified it as a ‘good’ gut microbe.

Let’s find out why.

What is Haemophilus parainfluenzae?

H. parainfluenzaeis a member of theProteobacteria phylum, a large group of gram-negative bacteria. Proteobacteria is the largest and most diverse phylum in the bacteria domain[i] and was discovered in the 1980s (the decade that Marty McFly time travelled in the DeLorean) by Carl Woese[ii].

The gut is the most colonised human organ.

In other words, it’s not just yours.

You share it with trillions of tiny microbes belonging to over 50 different phyla. Colonisation begins at birth, and your gut microbiome changes, stabilises, and diversifies throughout your lifetime.

However, other factors such as diet, age, exercise levels, medication, and smoking can affect its overall composition.

Your gut microbiota has many vital roles in your health, such as the production and metabolism of essential nutrients, like Vitamins K and B and short-chain fatty acids. It also helps maintain the integrity of your gut barrier; in effect, the stronger your gut lining is, the healthier you’re likely to be.

Proteobacteria is one of the phyla that helps to make up the gut microbiome and is one of the most abundant in the human gut. Many common pathogens are found within this phylum, including:

  • Escherichia
  • Salmonella
  • Shigella
  • Helicobacter
  • Haemophilus[iii].

Haemophilus parainfluenzaeis a common inhabitant or part of the normal flora of the mouth and throat; yes, bacteria live there too! H. parainfluenzaecan cause illness in people with weakened immune systems, such as children, the elderly, and the unwell [iv]. However, it is also found in a healthy human gut and researchers from the PREDICT study identified H. parainfluenzaein the gut of almost 55% of participants.

Is Haemophilus parainfluenzae a Pathogen?

Although it is a normal respiratory tract resident, research suggests that H. parainfluenzaeis also an invasive pathogen.

Before we look at some of the evidence, we should probably explain what a pathogen is. Pathogens are organisms that cause disease in a host. The severity of the symptoms is called virulence[v]. So, the more virulent a disease is, the more severe the symptoms will be.

Haemophilus parainfluenzaemay promote gut inflammation and increase the risk of developing inflammatory bowel disease, according to a study conducted in 2020[vi]. Interestingly, another study from the year 2000 found H. parainfluenzaein the sputum of patients with chronic lung disease. It suggested that in these patients, there is a species-specific systemic immune response to H. parainfluenzae[vii].In other words, this bacterium could play a pathogenic role in patients with chronic lung disease.

Further research also suggests that H. parainfluenzaemay cause specific bone and joint infections[viii].

The case doesn’t look great for Haemophilus parainfluenzae. However, the PREDICT studies have identified it as one of their 15 good gut microbes.

Let’s take a look at why.

 Pathogen to Pal: why Haemophilus parainfluenzae is a Good Gut Microbe

Despite evidence suggesting that H. parainfluenzae may be pathogenic, it is a commensal bacterium in the oropharynx. A commensal microbe acts on a host’s immune system to prompt protective effects against opportunistic pathogens[ix].

So, H. parainfluenzaemay have some benefits for humans after all, and that’s precisely what the PREDICT researchers believe.

According to their research, there is a link between H. parainfluenzaein the gut, lower insulin secretion, and increased insulin sensitivity. That’s important because too much insulin is not good for your health.

 Why is Too Much Insulin Bad for You?

Insulin is vital for controlling blood glucose levels, but too much of it can be harmful. Prolonged exposure to high insulin levels can be toxic and detrimental to many body functions[x].

Elevated levels of insulin that produce a weakened biological response, for example, with no decrease in blood glucose levels, is called insulin resistance[xi].

Insulin resistance is linked to the development of type 2 diabetes and occurs when the body no longer responds to insulin very well.

That means the cells are unable to take up glucose from the blood as they should, leading to prolonged high blood sugar levels.

How to Boost the Diversity of Your Gut Microbiome?

The key to good gut health is eating a balanced diet with plenty of natural, colourful foods. Increasing the diversity of the foods you eat will also diversify your gut’s microbial ecosystem[xii].

Your gut bacteria love to ferment plant-based foods, like fruits, vegetables, whole grains, nuts and seeds.

Another great addition to your diet for the promotion of good gut health is fermented foods. Good choices include:

  • Yogurt
  • Kefir
  • Kimchi
  • Sauerkraut

Don’t be fooled by all pickled vegetables, though! The best options are those fermented using natural processes and containing live cultures.

Many of the pickled vegetables in the supermarket are pickled using vinegar, so look for those fermented using live cultures instead.

Better still, why not ferment your own? There are plenty of workshops and online guidance to show you how.

One recommended resource is the site CulturedFoodLife.com, which is run by Donna Schwenk. Donna is incredibly passionate about cultured foods and offers many tutorials on how to ferment your own food and drinks.  

 Gut Health Hack: Human Milk Oligosaccharides

Human milk oligosaccharides (HMOs) are the third most abundant component of a human mother’s milk and are essential for the health of breastfed infants.

However, they have also been shown to have numerous benefits for adults too, including:

Want to find out more about how Fermented HMOs can support your gut health? Click here.


Haemophilus parainfluenzaeis an excellent example of how research constantly evolves and expands. Previous research has found that although this microbe is a common inhabitant of the mouth and throat, it has also been implicated in the development of bone and joint infections, and potentially promotes gut inflammation. Thus, classifying it as a pathogen.

However, more recent research from the PREDICT studies has found that H parainfluenzaemay have some health-promoting benefits.

For example, they have found it to be present in the guts of people who have lower insulin secretion and higher insulin sensitivity.

So, this bacterium may be beneficial in regulating blood sugar levels and may help prevent metabolic disease.

More research needs to be carried out to discover the effects of H. parainfluenzae, but what is certain is that the more varied your diet is, the more diverse your gut microbiome will be, and that can only be a good thing.


Written By: 

Leanne Edermaniger

Leanne is a science writer who specializes in human health and enjoys writing about all things related to the gut microbiome.

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[i] Mukhopadhya I, Hansen R, El-Omar E. et al. IBD—what role do Proteobacteria play?. Nat Rev Gastroenterol Hepatol 9, 219–230 April 2012. https://doi.org/10.1038/nrgastro.2012.14

[ii] C.R. Woese. "Bacterial Evolution." Microbiological Review 51 no. 2 1987:221–271.

[iii] Rizzatti G, Lopetuso LR, Gibiino G, Binda C, Gasbarrini A. Proteobacteria: A Common Factor in Human Diseases. Biomed Res Int. 2017;2017:9351507. doi: 10.1155/2017/9351507. Epub 2017 Nov 2. PMID: 29230419; PMCID: PMC5688358.

[iv] O'Neil CR, Wilson E, Missaghi B. Bone and Joint Infections due to Haemophilus parainfluenzae: Case Report and Review of the Literature. Can J Infect Dis Med Microbiol. 2016;2016:4503025. doi: 10.1155/2016/4503025. Epub 2016 Jul 19. PMID: 27516778; PMCID: PMC4969501.

[v] Balloux F, van Dorp L. Q&A: What are pathogens, and what have they done to and for us? BMC Biol. 2017 Oct 19;15(1):91. doi: 10.1186/s12915-017-0433-z. PMID: 29052511; PMCID: PMC5648414.

[vi] Shapiro J M, de Zoete M R, Palm N W. et al.Immunoglobulin A Targets a Unique Subset of the Microbiota in Inflammatory Bowel Disease. Cell Host & Microbe. 2021 Jan 13; 29(1). https://doi.org/10.1016/j.chom.2020.12.003

[vii] Mitchell JL, Hill SL. Immune response to Haemophilus parainfluenzae in patients with chronic obstructive lung disease. Clin Diagn Lab Immunol. 2000 Jan;7(1):25-30. doi: 10.1128/CDLI.7.1.25-30.2000. PMID: 10618272; PMCID: PMC95817.

[viii] Conar R. O’Neil, Evan Wilson, Bayan Missaghi, "Bone and Joint Infections due to Haemophilus parainfluenzae: Case Report and Review of the Literature", Canadian Journal of Infectious Diseases and Medical Microbiology, vol. 2016, Article ID 4503025, 5 pages, 2016. https://doi.org/10.1155/2016/4503025

[ix]  Khan R, Petersen FC and Shekhar S (2019) Commensal Bacteria: An Emerging Player in Defense Against Respiratory Pathogens. Front. Immunol. 10:1203. doi: 10.3389/fimmu.2019.01203

[x] Kolb H, Kempf K, Röhling M. et al. Insulin: too much of a good thing is bad. BMC Med 18, 224 2020 August https://doi.org/10.1186/s12916-020-01688-6

[xi] Wilcox G. Insulin and insulin resistance. Clin Biochem Rev. 2005 May;26(2):19-39. PMID: 16278749; PMCID: PMC1204764.

[xii] Heiman ML, Greenway FL. A healthy gastrointestinal microbiome is dependent on dietary diversity. Mol Metab. 2016 Mar 5;5(5):317-320. doi: 10.1016/j.molmet.2016.02.005. PMID: 27110483; PMCID: PMC4837298.

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